Part 2: Wireless Charging for Vehicles // The Nitty Gritty Details

[@steverobbins4872]

I'm a retired EE. I commented on your Part 1 video that I didn't see how wireless charging could be reasonably efficient because of all the leakage flux. Since then I've come to realize how resonance could be used to significantly reduce this problem. Here's how: 1) Leakage is typically modeled as an inductor (the so called "leakage inductance") in series with the tranformer's primary winding. 2) When you place a capacitor in series with the primary (a capacitor used this way is typically called a "coupling cap") would look like a series-connected LC before the primary winding. In other words, the coupling cap and leakage inductance form a series-resonant circuit. 3) The key thing to know about series-resonant circuits is that their impedance drops to nearly zero at the resonant frequency. This would, in theory, mitigate the problem of leakage flux. 4) The coupling cap would have a fixed value, while the leakage inductance can vary depending on the relative positions of the two coils. So the frequency would have to be adjusted to find the resonant peak.

[@thelimitingfactor]

Thanks for following up! 🤠

[@mikebailey2970]

my wife suggested they install a charging pad to fill in the potholes in the existing roads. 8) (love her humor)

[@thelimitingfactor]

😂

[@helmutshotthesheriff1942]

That a very "interesting" wife...😂👍 👍

[@SparkySho]

It’s that easy ??? grinnin bigly again

[@chrisoconnell8432]

If the Optimus had wireless charging in its feet then it could stand on the charging pad while continuing to work. This would be useful for any type of work where the robot doesn't move much from its workstation.

[@gtyang81]

I believe for cybercabs, Tesla will plan its deployment according to peak demand as predicted by James douma. Hence, most cars will be underutilized, and thus they will have plenty of time to charge - charging speed will not be as critical. They only have to make sure all the cybercabs have sufficient charge during peak hours.

[@thelimitingfactor]

Agreed

[@Matzes]

The management and logistics of a robotaxi fleet in the millions is utterly fascinating to me. I hope to see a video on this channel about it in a few years.

[@geirmyrvagnes8718]

Slight correction: The power for a 250 kW Supercharger is not necessarily enough for 10 25 kW chargers. The power is shared between superchargers, since charging rate is limited by the cars/battery, so there is no need to have the electronics and power supply for all the Superchargers at a site to be working at 250 kW at the same time. For 25 kW charging, almost all the cars/batteries will be capable of drawing 25 kW, so sharing power does not give you an investment saving without significantly sacrificing charging speed when most of the stalls are occupied. So about 5 or 6-ish 25 kW charging pads for a 250 kW Supercharger. Or so. Roughly.

[@johnbaker5533]

Missed this comment before I post but it is more likely to be less than that at about 3.6 cars for stall. 4 V3/V4 superchargers are powered by 1 V3 cabinet which get in 387KVA. That is likely about 360kW when converted (unknown efficiency for the power factor) which is 3.6 cars per 250kW V3 stall. I think they will build new facilities for charging. Space is a major limiting factor instead of converting existing supercharger sites.

[@geirmyrvagnes8718]

@@johnbaker5533 Yes, we basically agree. Assuming your numbers, you can power 3.6 cars at full power for 25 kW chargers. So if you accept a little bit of power sharing, 4 or maybe a little more chargers. My gut feeling of 5-6 wasn't that far off. 😇Obviously, it is an academic exercise. The power electronics will be very different, so this will be new installations, since hooking up to the DC power supplies for Superchargers is not how this is done.

[@SparkySho]

@ 15:42 liquid cooled with windshield washer fluid… I’m fairly sure makes sense to me @ 15:?? Optimus wireless when STATIONARY gon work

[@tysonjbest]

As contractor its allways preferable to face out in any parkin situation in adverse weather so rear pad charging sounds smartest;)

[@thelimitingfactor]

Amen. Professional driving technique.

[@brianstanfill2114]

Your work is really fantastic. Thank you for this.

[@thelimitingfactor]

You're most welcome!

[@SparkySho]

The Limiting Factor is th very best technical video engineer on utube easily no competition between on

[@MikesTropicalTech]

The on-the-ground pads are going to be difficult in outside lots where it snows. They're going to need to be embedded and flat.

[@SparkySho]

Heat trace melts snow pads will be obvious

[@MikesTropicalTech]

@@SparkySho Yes but to clear the entire parking space of snow the units and cables are going to be scraped right off the ground.

[@tadeasmejdr5091]

Optimus charging should be done with the old Tesla charging snake ;)))

[@thelimitingfactor]

😂

[@andrewpaulhart]

@@tadeasmejdr5091 and a little imagination on where the socket is positioned on the humanoid robot could give tesla much free publicity

[@IndigenousEarthling101]

I think Tesla may also provide their wireless charging pad supply cables with NACS adapters to connect directly to existing Tesla Wall Connector home chargers and Superchargers.

[@thelimitingfactor]

I think it depends on the vehicle. I'm betting the Cybercab won't have a cable at all.

[@francis_lang]

I believe indigenousEarthling101 meant the wireless charging pad will ship with the cabling necessary to connect to existing wall connectors and moble chargers with a female adaptor.

[@MrFoxRobert]

Thank you!

[@JT-ss1xo]

I think for Optimus it makes a lot of sense to have a normal, short power lead. That way, it can continue to work on the tether, and it can plug in literally everywhere.

[@markplott4820]

it should have ungrounded 120v cord dragging from its butt........lol.

[@ccibinel]

This really does seem like the simplest. In a few hours of 120v it can charge itself while in any stable posture. Once you have a flexible robot no need to complicate the charging since 120v power is everywhere and 240 is definitely possible in industrial settings if you want it faster. A new standard is unnecessary for optimus.

[@w0ttheh3ll]

Wireless charging roads on a large scale aren't going to happen anytime soon for the same reason that overhead power lines for electric trucks aren't going to happen anytime soon. As you pointed out, this kind of infrastructure is very expensive. It can only happen if a very powerful entity pays for it. It can only be profitable if the tech is massively adopted. Say for example a government pays for the construction and forces mass use. As long as it's not totally clear that these are good solutions, no government is going to even attempt it.

[@thelimitingfactor]

I agree!

[@rymaples]

Heck, many people believe EV vehicles aren't the future. It'll be a long time before anything futuristic like wireless charging roads ever become a serious topic.

[@helmutshotthesheriff1942]

As usual, intersting to the smallest detail ❤👍 👍 👍

[@Clark-Mills]

WRT public charging; similar to the problem with CCS and the latch that's attached to the public charger - any moving part that's on a public charger is liable to damage. The logical solution is to have mostly flush inductive loops embedded in all parking spots in a standard location. It is then the job of the vehicle to seek and optimise the sweet-spot for charging; and similar to the latch in a NACS/Tesla vehicle socket... if the moving part gets damaged, it's the cars problem and the charger can serve the next customer.

[@ThisRandomUsername]

I was of the understanding that Qi chargers were also resonant chargers where both the coils operate at a constant resonant frequency. Maybe they're talking about being able to tune the resonance with various capacitor banks like in some RFID readers. This will let you increase the Q (basically the peakiness) of the receiving and transmitting coils.

[@thelimitingfactor]

Qi is inductive, not resonant inductive. That's why it doesn't work with a signifcant air gap

[@LoueeD]

A big benefit for Optimus would be the lack of a on-board charger (OBC), less internal complexity, less weight, more room for batteries. "The best part is no part" I'd love to see a video on manufacturing Optimus as scale.

[@brucebender5917]

IMHO the cybercab fleet will be owned and operated by Tesla, and rolled out city by city in tandem with wireless charging. First cities covered will be the cities that Cruise and Waymo have been operating in as these municipalities have already greenlit the regulatory approvals for autonomous ride hailing. It will be interesting to see how much market share each company can capture. . . .

[@andrasbiro3007]

Tesla is planning to make them by the millions. A slow deployment won't keep up with that volume.

[@geirmyrvagnes8718]

@@andrasbiro3007 It would keep up for a short while. Those are some big cities. It will not be dominating the traffic in New Delhi two seconds after it starts production. Some patience is required.

[@MrAlRats]

It will be interesting to see how long it takes Tesla to establish a virtual monopoly on autonomous ride hailing. Chinese/Korean EV manufacturers could be the first to license and implement Tesla's FSD in their vehicles.

[@ccibinel]

Great video. I was always skeptical about the efficiency of this technology but for easy charging in parking lots it makes sense but the equiptment is expensive enough that parking enforcement for the spaces will be important. I do wonder if the standard has any handshake to allow for billing.

[@rzee4331]

Angled parking and parallel parking would be problem if vehicle charging pad location is not standardized. Putting ground pad near curb makes sense since vehicle length can vary, but backing into angled spot has its problems.

[@geirmyrvagnes8718]

Maybe the parking spots in question would be rebuilt for straight parking when the chargers are to be installed. Or the chargers will be installed in other spaces.

[@chrisheath2637]

For "in road" wireless charging to be feasible - it requires places where cars stop regularly and predictably. The cost for continuous road wireless charging would be ridiculous. Road costs are high enough - without adding additional layers of technical complexity. Traffic lights are an obvious place where "several" wireless charging spots could be sited. Power is there (traffic lights ), cars regularly stop there. Payment for charging ? Car parks may be easier - blocking off a few spaces for works, is better than closing a lane or two in a road...but ICEing may be a problem...

[@darrenschmitz2712]

For another safety feature the car's camera could scan the wireless charging pad for debris before deciding to drive over it.

[@drewcress]

A notable plus for wireless charging (that I don't believe was mention in your pervious videos) is a shared inverter helps lower the fleet coast. While an on car inverter is handy for a personal vehicle, the charing inverter can't be used when it is too is being driven about. For a commercial fleet it is likely more cost effective to drop AC support on the vehicles and adapt the parking lot. Odds are the in car inverted will outlast the car itself anyway, so it is just one less thing to part out.

[@thelimitingfactor]

🎯

[@geirmyrvagnes8718]

The current from the coil is also AC, just at a different frequency. The charging electronics will be different, not disappear as it would in a DC charging only vehicle, roughly and hypothetically speaking.

[@Clark-Mills]

WRT inductive loop charging: Similar to how our phones charge... there's also data encoded in the magnetic pulses. The charger is constantly sending out a weak sense pulse - when a vehicle is overhead with its inductive loop it communicates back via magnetic pulses stating it's capabilities. As the induction field is ramped up, the vehicle notifies the Charger how much charge it is receiving. The Charger knows how much it is sending and if there's a discrepancy (outside set tolerances) the charger can disengage the charge session. If the Charger senses expected energy transfers the charger can continue to ramp up the energy transfer. This monitoring of energy losses is constant so the charger can cut power at any time and signal an error. Plonk a bit of iron on your inductive phone charger and you'll see this safeguard in action.

[@Clark-Mills]

Wikipedia: Qi is an open standard for inductive charging developed by the Wireless Power Consortium. It allows compatible devices, such as smartphones, to receive power when placed on a Qi charger, which can be effective over distances up to 4 cm (1.6 in). Devices that implement the optional Magnetic Power Profile for magnetic attachment and alignment may be labelled Qi2. Qi version 1.0 was released in 2010; by 2017, it was incorporated into more than 200 smartphones, tablets and other devices. As of December 2023, there are 351 manufacturers working with the standard including Apple, Asus, Google, Huawei, LG Electronics, Samsung, Xiaomi, and Sony.

[@thelimitingfactor]

Cool!

[@jamesbootman1149]

Reduced battery pack Cybercabs and shipping container tenders in Boring Co. tunnels with wireless charging hardware in the tunnel slice under he road sounds like a clean kill to me.

[@sandcrabfin]

The most important aspect of wireless charging systems is to have a robust standardization framework, that is ensuring that cars can easily perform short-distance automatic docking and that the payment system operates seamlessly. For most use cases 22 kW should be sufficient, as the most likely installation locations for these chargers are homes, workplaces, or malls. At workplaces 11 kW is more than adequate since cars are typically parked for 8 hours. During that time an 11 kW pad could charge a 100 kWh battery from 10% to 90%. For malls, where the average visit lasts about 1 hour, a 22 kW charging rate would provide an additional range of at least 100-150 km (50-75 miles) for the average user. Robotaxis and similar applications will likely remain niche products, and for these there may be room for higher-cost hardware in both cars and charging pads. However for the majority of installations, the primary driver will be affordability to enable easy scaling into a ubiquitous system.

[@chrisheath2637]

It's always possible that Tesla owners can "opt-in" to the wireless charging network (and get paid), so robotaxis can charge on their pads in the driveway...

[@ludwigbear]

Charger would have to be buried in regions that get snow otherwise the pad is going to get damaged when you scrape the snowblower over the top

[@geirmyrvagnes8718]

Definitely. Or of course, they can be indoors.

[@peterzerfass4609]

Since Optimus can be very precise in its movements I don't see issues with high wear and tear on a wired charger that would lead to frequent maintenance. There is little chance of it making the kind of accidental/harsh movements that a human user might do out of negligence. Conversely the wired charging unit seems to be rather large and space (and weight) is at a premium for Optimus so that would speak against its use there.

[@thelimitingfactor]

Good points!

[@nitroushhh]

Might optimus put itself on the hook so it doesn't need to stand while charging? If it's standing it needs to sense and balance and that uses charge. If it's not balancing then it's inference compute could be network shared.

[@johnpoldo8817]

As an individual EV owner, I would never go to a wireless supercharger for 20kW because a 50kW charge would take 2 1/2 hrs. Application seems to be Robotaxi, fleets, or home install.

[@Clark-Mills]

In an ideal world there would be inductive loops in all car parks and parking would be free so long as the vehicle participates in a VPP. Users can opt out and pay the penalty (power cost plus parking) as there may be those preparing for a long journey. RoboTaxies (from all providers) would be happy with this setup too as the vehicles are distributed everywhere. This requires big-picture oversight however as businesses like their walled gardens...

[@Clark-Mills]

Another advantage of street-flush inductive loops: The Vehicle inductive loop can descend and find the sweet-spot over the Charger Loop. This will mean that the vehicle metal mass (chassis, motors, suspension, battery-pack) will be a goodly distance from the Charger-Loop and will consequently minimise eddy-losses / localised-heating in the vehicle chassis.

[@gridcoregilry666]

stellar as always!

[@thelimitingfactor]

Thanks man!

[@jeffharmed1616]

IMHO skateboard chargers would be optimal for Optimus on the factory floor. Optimus could continue its tasks whilst riding the skateboard chargers

[@saurabhchandra6267]

Reversing into a tight parking slot is always easier than doing it forwards.

[@markplott4820]

see - Tesla FSD tightest parking EU.

[@geirmyrvagnes8718]

...in your opinion. I prefer it that way myself, but I can see that the sideways precision of the end of the vehicle going in first will be better on average if a randomly selected driver goes in forwards, which was the issue in question.

[@martinbeverley9536]

For Optimus to use wireless, its charging pad will have to be small and light. Weight seems to be an issue with Optimus, so wired charging would make sense, at least for the early generations. A 25kw wireless charger will take a long time to charge a car. This doesn't sound practicable, except for things like Cybercab.

[@thelimitingfactor]

Good point!

[@martinhicks6020]

Optimus robots could still hook themselves onto a wall bracket and have a wireless charger on their backs. The wall would have a charging pad mounted vertically below the hook.

[@ccibinel]

The robot has the dexterity to plug itself in with a simple extension cord. The only downside to this would be that the robot would need to be tailored to the connector or voltage of each country.

[@geirmyrvagnes8718]

@ There could be other upsides to dedicated charging. It can be more reliable and slightly smarter and do power sharing. But the robots themselves are smart enough to do that, too.

[@stcredzero]

Remember the Cruise taxi that dragged the woman under the car in San Francisco? All self driving vehicles should have a camera under the car. This could also be used to detect metal on top of the inductive charging pad.

[@piotrsuszynski9273]

An idea: the coil in the power pad could move inside the pad to align itself perfectly with the coil in the car.

[@MB-xz7ls]

That would just increase the cost and maintenance. Why to move mechanism in pads when you have autonomous cars that can park precisely.

[@thelimitingfactor]

🎯

[@thelimitingfactor]

No need. It just adds cost.

[@piotrsuszynski9273]

Maybe it would still be worth it because this enables millimetre precision and those chargers will be used a lot of times over many years and the charging efficiency gains will add up. Assuming automatic parking will result in 1 inch misalignment on average what would be the efficiency loss from such misalignment as compared to a perfect one?

[@b0570nk4]

selling a hardware that enables wiresless charging is a product that generates revenue on its own, but it would also increase the technical service required for repairing and fixing, while that too can be profitable, it would affect their current factory layouts so "making space in an already tight space" would be required the biggest argument in my eyes is that both tesla and customer saving on cables and socket adapters, etc, and hopefully that the whole industry will decide to synchronize on the same communication protocol / frequencies technology and/or standard rather than each developing their own, incompatible version --- and let's be realistic, older car manufacturers are unlikely to be inovative enough nor willing to adapt straight away - just look at the NACS topic where there still are a lot of brands who don't have it

[@thelimitingfactor]

I don't understand this. Wirless is less likely to break. Less moving parts. It won't have an affect on factory layouts either, other than to make them simpler.

[@b0570nk4]

@@thelimitingfactor i hope so, i only made a speculation that it may hypothetically bring new technical problems tesla would have to be dealing with, - lets hope i am wrong haha

[@Kevin-xt1er]

If ownership of cybercabs is profitable, hope that Tesla will give the old Tesla owner priority to buy. One for each bought.❤

[@TedKidd]

10:40 Cybertruck has wireless charging?

[@thelimitingfactor]

The headers

[@chrisroger2000]

Why not have the wireless charging receiver in the middle of the car rather than front or back? That way, the car can park forwards or backwards into the spot and still accept the wireless charge no matter if a human or “cyber-cab” does the parking.

[@keegantoneguzzo3580]

Probably because the battery takes up most of the space between the wheel ( middle of car), leaving front and rear space for charging/electronics

[@thelimitingfactor]

🎯

[@rhamph]

Every vehicle has a different length, so what you need is a consistent distance from curb/wall, allowing them to park correctly when charging. Front vs rear doesn't matter, so long as you know which way your vehicle goes.

[@piotrsuszynski9273]

What about people with implanted heart pacemakers - is wireless charging safe for them?

[@ThisRandomUsername]

Theoretically. There was a study that placed an iPhone to peoples chest that was shown to have some effect on pacemakers. This seems to have been just the phone, so I would actually wonder if it was the NFC instead of the Qi receiver. However, remember that the intensity of a field is inversely proportional to the square of the distance from the emitter. So I guess if someone fell over on top of one of the chargers it could have an effect on a pacemaker. However, according to the SAE J2954 Wikipedia page, the chargers communicate with the car via Bluetooth, so it would probably not even activate unless a car was in the way, absorbing most of the radiation.

[@thelimitingfactor]

Tested, no issues

[@piotrsuszynski9273]

@@thelimitingfactor already tested? Also for those high power car chargers? Would you mind sharing the links to those tests/studies?

[@geirmyrvagnes8718]

It would be a bigger problem for the poor old lady with the pacemaker that she is now squeezed under a parked Tesla.

[@eclecticcyclist]

Wireless charging roads make no economic or practical sense, since the charging can start as soon as the car is positioned and handshaking is complete, top up charging a car is likely to be quick and easy.

[@Bryan46162]

They are not right around the corner for sure, but a wireless charging road would have HUGE benefits. Namely, allowing vehicles to road trip while having tiny batteries and thus be a very cheap vehicle to purchase. Or to eliminate towing anxiety for the pickup crowd. You don't even need to blanket all roads with wireless charging. You could start at hills, meaning that you eliminate the parts of the journey that cause the most energy drain.

[@jamesengland7461]

​@Bryan46162 but nobody can even build proper roads, much less maintain them, not to mention running high voltage electrical thru them. That's just waaaaay too much to be doing.

[@bertiewalker5140]

If each element has at worst case 2% loss, for a 250W power transfer this means dissipation is only 5W really not hot at all so no liquid cooling is needed surely. If liquid cooling is needed then clearly it is not as efficient as they are saying. I admit ignorance here.

[@vipondiu]

I think that if the metallic collar wearing cat is in the few centimeters between the car and the charging pad, that cat is already dead

[@thelimitingfactor]

Cats are a liquid 😁

[@andrewpaulhart]

not convinced that the robustness of wireless would outweigh cost. should be trivial to make contacts in such a way that replacement would be cheap and trivial. however wireless might allow charging at the robot workstations in order to allow charging while. it is working. that would significantly increase the value of the robot. having said that wired charging at workstations would also be possible in the same way that we use our mobile phones while they are plugged in. for mostly stationary tasks optimus could plug and unplug itself as it moves around the factory when it switches between tasks

[@johnbaker5533]

For the 10 wireless per 250kW V3/V4 supercharger that is not right. Supercharger share power based on 4 stalls per cabinet (and then power share via a bus between cabinets) 4 V3/V4 superchargers are powered by 1 V3 cabinet which will be 387KVA. Unclear what the conversion to kW as the power factor is unknown but likely 360kW or so there you are likely to get 3.6 cars powered for every 1 stall. Personally I can't see them ripping out superchargers for this more likely they will have a separate facility for it.

[@thelimitingfactor]

Nah, they won't rip out existing superchargers. They're very capital efficient.

[@joe55514]

wouldn’t it be smart for Optimus to hot swap batteries to get mback to work immediately. seems like a huge waste to let it wait for charging

[@Modok51]

Wow, how about a portable wireless charger that can be placed in the trunk! This would allow apartment dwellers to recharge the charger inside the house & charge vehicles overnight on the streets! I know, I know, we will have to overcome the laws of physics,not to mention the weight of the device!

[@SparkySho]

5 : 20 tysm for covering that…… hydrogen explosions are not happening man safe ANY AGE

[@Poxtheengineer]

People at Renault: put wireless charger into the passenger door 😁

[@thelimitingfactor]

🤣

[@erictheblue7256]

I live in a multi-unit condo with a dedicated, covered (but not enclosed) parking space. A buried charging plate would allow me to charge securely, as vagabonds and derelicts on the street passing by would have no knowledge of the system or ability to steal it. I'm very excited for future of wireless charging for widespread consumer and commercial use.

[@SparkySho]

Very

[@budgetaudiophilelife-long5461]

🙋‍♂️🤗THANKS AGAIN JORDAN AND YOUR SUPPORTERS AND JEREMY FOR GETTING INTO THE “ nitty gritty “🤗😁⚡️⚡️⚡️

[@TheLastMoccasin]

Pretty sure most Tesla customers would rather have Tesla improve their charging curve which has really fallen behind rather than this wireless charging distraction...

[@thelimitingfactor]

Two different technologies for two different purposes And no, most Tesla customers don't care It's a small, fringe group of people that are obsessed with charging speed

[@TheLastMoccasin]

@@thelimitingfactor Yea, you are correct... most Tesla customers don't care... because customers that do care are buying other brands, or still buying the fastest charging vehicles (ICE cars). But to convert those customers to buy a Tesla (something Tesla needs to do better with sales declines) they need vehicles that beat the competition in all aspects (like they used to have) and that incudes charging.

[@johns.r.lawrence9287]

What about the interaction with pacemakers?

[@thelimitingfactor]

It's been safety tested for that. You can easily look this up online by punching in the charging standard I mentioned.

[@MAESTROLIDER]

Спасибо за интересное видео. Мы в 2018 году на беспилотный электробус хотели поставить беспроводную зарядку , но отказались от этой идеи (точнее отложили это решение).

[@tysonjbest]

Wouldnt it be kool if the first burst of power energises a magnetic ring to pull the connection into perfect alignment😉

[@geirmyrvagnes8718]

Sounds like extra moving parts. 😇

[@thelimitingfactor]

🤣💯